Panic: unexpected kvm exit reason 8 about gokvm

[bobuhiro11]

@zyedidia Thanks for reporting issue.
For some reason KVM seems to be exiting with KVM_EXIT_SHUTDOWN as you said.
But, I was not able to reproduce it on my laptop (Intel i7-5500U, Ubuntu 20.04 LTS).
I would like to reproduce it if possible, so could you provide some additional information?

• CPU
• Host linux distribution
• Host linux kernel

[zyedidia]

Here is the additional information:

• CPU: Intel i7-1165G7
• Host linux: Ubuntu 21.10
• Host kernel: Linux 5.13.0-28-generic

Thanks for your help! I will also try on a different machine when I get the chance.

[zyedidia]

Is it possible KVM shut down because of the message Speculative Store Bypass: Vulnerable? Is there an internal KVM log, or something that would help understand why it decided to send a shutdown signal?

[bobuhiro11]

Hmm, I'm not sure if the guest will shut down due to CPU vulnerability or its mitigation. As you may know, the code under arch/x86/kvm outputs debugging information with the pr_debug function, which you can see by using dynamic debug [1].
If you're concerned around CPU vulnerabilities, how about temporarily disabling all mitigations by adding mitigations=off to the command-line parameters?

For your information, my command-line parameters and CPU information are as follows.

$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-5.11.0-41-generic root=UUID=9c174809-4f37-4add-b76f-8f2ea977649a ro

$ lscpu
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   39 bits physical, 48 bits virtual
CPU(s):                          4
On-line CPU(s) list:             0-3
Thread(s) per core:              2
Core(s) per socket:              2
Socket(s):                       1
NUMA node(s):                    1
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           61
Model name:                      Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz
Stepping:                        4
CPU MHz:                         600.000
CPU max MHz:                     3000.0000
CPU min MHz:                     500.0000
BogoMIPS:                        4788.73
Virtualization:                  VT-x
L1d cache:                       64 KiB
L1i cache:                       64 KiB
L2 cache:                        512 KiB
L3 cache:                        4 MiB
NUMA node0 CPU(s):               0-3
Vulnerability Itlb multihit:     KVM: Mitigation: VMX disabled
Vulnerability L1tf:              Mitigation; PTE Inversion; VMX conditional cache flushes, SMT vulnerable
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via prctl and seccomp
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Full generic retpoline, IBPB conditional, IBRS_FW, STIBP conditional, RSB filling
Vulnerability Srbds:             Mitigation; Microcode
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopolo
                                 gy nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm
                                  3dnowprefetch cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid rdseed adx smap intel_pt xsaveopt dt
                                 herm ida arat pln pts md_clear flush_l1d

[1] https://www.kernel.org/doc/html/latest/admin-guide/dynamic-debug-howto.html